the sweating thing is tuff. The moisture will work away the adhesion of the wafer. when I know I am going to sweat alot, I use waterproof tape to "picture frame" the wafer so the edges stay secure. I have a picture of this at: www.theamericanostomyclub.com
the belts helps too. I have had 5 hernias. do everything you can to KEEP those from happening. Nu-Hope makes a great hernia brace that does a great job keeping everhing in place. try that too.
also when I do a lot of bending, I turn my bag sideways for a while so it does not get in the way. Turn it back down when you are done so the waste flows away from the stoma properly. I never had a problem with the bag sideways for a short time.